Slow91z

I was wondering about the advantages of the duel converter set up....seems to me that two cats will flow a lot better then one (twice the flow area)....I have a 91z with a single cat, would it be worth it on a slightly modded engine, and would the adavantages increase with a more seriously hardcore powerplant??? Also if I bought headers and y-pipe and cat back exaust all for a duel cat car what other mods would be necassary (like A.I.R.) Food for thought

fbird95

Only a slightly moded engine i would say no. If you got plans for a crazy power plant, than they would have greater impact. Unfortunatly on a bigger power plant, you might not want to spend the extra cash on a few extra horses, where as with the slightly moded engine you may wnat those few extra horses.

kandied91z

go single 3" with a 2 chamber exhaust to single out....you'll see some nice gains.

i have a custom y with the piping and a flowmaster for sale for 350 if your interested.

irocz8957

if i was you i would just get an off road pipe so that you can take your cat off and put it back on when yo want to cats are a huge choke hold on cars thats why i yanked mine off!

aklim

I went to the single cat system when I redid my exhaust and went with a Random Cat. They are supposed to be high flow and not sap too much power. I made a run with the cat on and disconnected it and did not notice any substantial gains.

Slow91z

I do know that John Lingenfelter tested the stock cat set-up on LT1 cars and found that they were not a real restriction until you got deep in the 11's....Also the more flow area you have before the Y-pipe the better because it help's out your low end torque without loosing any upper RPM horsepower....Anyone know anything about the differences between the A.I.R. systems on the single vers. duel cat. cars??? To bad I can't just run duel's with an X-pipe....those X-pipe systems are amazing, they loose like one HP in the upper RPM's as opposed the open exaust, but have great torque down low

aklim

If memory serves me, all that was different was that the AIR pipe branched off into each of the cats. Kinda of a "Y"

Bristol

I have a 91Z and have/had the dual cat setup. My buddy runs a shop so we made a wicked custom Y-pipe without the cats. Then further down the pipe we cut out a 1ft. section and bought a single cat and 2 Walker sheet metal clamps. Now I drop the cat in for emissions and pull it and replace it with the straight pipe for the rest of the year. Takes a wopping 5 min. to do the swap and the car sounds great too. I dont really have any pics cause its hard to get some on the ground but I will get some on the hoist

Bristol

Anyone know anything about the differences between the A.I.R. systems on the single vers. duel cat. cars


The only difference I see is that that single air pipe goes into a junction the splits to each cat.

Slow91z

Well that's cool....I guess I'll probably start looking into prices on duel cat systems now, thanks guys

aklim

You can never find prices on duel cats because they don't exist AFAIK. You should look for DUAL cat setups if you really want it. I'd go with a high flow single cat which can be removed for race purposes.

Slow91z

What do you mean you can't find them?? Everytime I look at a cat back exhaust or a header setup I always see them for duel or single cats clearly marked....All I should have to do is buy a duel cat header system and a duel cat cat-back exhaust, then buy two high flow cats and modify a A.I.R. tube to go to both of them....If I'm missing something someone please fill me in....Thanks

aklim

If spelt correctly you will see them for "DUAL" not "DUEL". A Duel is a fight. Dual means two.

I had Global West subframe connectors and they constantly rattled witht he DUAL cats so when I switched the exhaust system, I went to single cat. I used a Random high flow cat.

Slow91z

My bad, I wasn't much on spelling in school, I was to busy working on cars....But my point is with two high flow cats I'll have twice the flow area and less back pressure, therefore more upper RPM Horses and More low end torque

aklim

All it does is make the "Y" come on at one point or another. On a single cat setup, the "Y" comes before the cat. In this case, the "Y" comes after the cat. It all still dumps into the same exhaust pipe at the end of it.

I doubt there are serious gains for the money or effort. If you are racing and every thousandth of a second counts, maybe. I doubt that the cat is the choke point where if you were to let it go thru 2 cats instead of 1, the resistance is better on 1. If you are that concerned, run a single cat setup and make it such that you can unbolt the cat and run a test pipe thru it.